Remote monitoring system for detecting termites

ABSTRACT

The subject invention pertains to materials and methods useful for monitoring and management of certain pests well as other biotic and abiotic factors. The invention is particularly well suited for the control of social insect pests, and particularly, termites. The invention concerns methods and apparatuses for monitoring pest activity and presenting a toxicant. The invention is useful as part of an Integrated Pest Management Program and can significantly enhance the efficacy, efficiency and convenience of the management program.

BACKGROUND OF THE INVENTION

Houses and other structures are constantly subjected to damage caused byfactors such as, for example, insects, pests, fungi, and excessmoisture. Indeed, such factors may even pose a risk to the well-beingfor the inhabitants. Inspections for damage caused by these and otherfactors are typically conducted manually at either regular intervals oron an as-needed basis. Manual inspections, however, are often costlybecause inspectors must be present at the site. Moreover, manualinspections of this nature may prove to be quite invasive, insofar asinaccessible or otherwise remote portions of a given structure mayrequire significant disturbance to walls, ceilings, etc., therebyresulting in added inconvenience and expense. Further, if the manualinspections are not conducted in a timely fashion, severe damage to thestructure may have already occurred by the time the damage is revealedthrough a manual inspection. This can be especially true if the damagingfactor is subterranean termites.

Subterranean termites most often enter structures from the surroundingsoil to feed on wood, or other cellulosic material, of the structure andits contents. If unchecked, termites can cause considerable damage. As aresult, efforts to erect physical or chemical barriers to prevent theentrance of termites into a structure or to exterminate the termitesafter they have invaded a structure have proven a considerable expenseto the public (Su, N. Y., J. H. Scheffrahn 1990! Sociobiol.17(1):77-94). The cost to control termites in the United Stated exceedsone billion dollars annually (Mauldin, J. K. S. C. Jones, R. H. Beal1987! The International Research Group on Wood Preservation Document No.IRG/WP/1323).

Subterranean termites construct an extensive foraging gallery beneaththe soil surface. A single colony may contain several million termiteswith foraging territory extending up to 300 feet (Su, N. Y., R. H.Scheffrahn 1988! Sociobiol 14(2):353-359). Since subterranean termitesare a cryptic creature, their presence is not normally known until aftersome damage, foraging tubes, or live termites such as swarmers, arefound. Some subterranean termites are know to forage beneath an objecton the soil surface (Ettershank, G., J. A. Ettershank, W. G. Whitford1980! Environ. Entomol 9:645-648).

Certain methods and apparatuses have been suggested to monitor for andcontrol pests such as subterranean termites. For example, InternationalPublication No. WO 93/23998 (Dec. 9, 1993) discloses methods andmaterials for pest management which include a series of connectedmonitoring blocks that are placed in soil adjacent to and surrounding astructure foundation. A thin strip of conductive metal is embedded ineach monitoring block such that a contiguous circuit is formed by theconnected monitoring blocks. Severe infestation by termites in themonitoring block results in the breaking of the contiguous circuit,which can be registered by an electronic device. Despite its manyadvantages, however, an arrangement of this sort can be relativelycumbersome in particular applications. This arrangement also requiresthe presence of a technician to conduct on-site monitoring. Moreover,since the point of circuit breakage cannot be readily isolated, itsometimes may be difficult to promptly determine the precise location ofsensed termites.

It is therefore highly desirable to more efficiently and effectivelymonitor for biotic and abiotic factors, such as insects and other pests,fungi, and excess moisture, so as to minimize damage that may be causedby such factors. It is especially desirable to more efficiently andeffectively monitor for the presence of subterranean termites.

Other objects and advantages of the present invention will be apparentto those of skill in the art, based upon the figures and the followingdescription.

BRIEF SUMMARY OF INVENTION

The invention disclosed and claimed herein relates to a system useful inmonitoring for a variety of biotic and abiotic factors, and perhaps mostadvantageously in monitoring for insects and other pests. Specificallyexemplified herein is a system useful in monitoring for insects of theorder Isoptera, particularly, termites.

One preferred system is useful in the monitoring phase or step of atwo-step process for controlling termites, wherein one step ismonitoring and the second step is control. The system of the presentinvention may conveniently provide for efficient monitoring of a givensite for pest and/or other target factors. The resulting reduced oreliminated need for on-site manual inspections may allow for morecomprehensive monitoring. Zones having at least one sensor each arechecked on demand or pursuant to a specified schedule. If desired, thesystem may be configured in a manner that allows the location of sensedtermite activity to be associated with a particular sensor or group ofsensors. Data relating to the status of the sensors may be forwarded orretrieve for storage, recordal, review and/or analysis at a remotelocation. The system can be configured to conveniently provide formonitoring and other data exchange between the target site and remotelocations using existing communications means.

As described more fully herein, there are a variety of methods andapparatuses which can be used to realize the system of the subjectinvention. The precise methods and apparatuses which would be optimalfor a particular target factor and environmental setting would beapparent to a person skilled in this art of using the teachings providedherein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic representation of an example remote monitoringsystem, including a data collection unit that communicates with a hostsystem at a remote location to provide data obtained from sensorslocated at the target site.

FIG. 2 shows a schematic representation of another example remotemonitoring system configuration, including a data collection unit thatcommunicates with a plurality of sensors using a plurality of individualcommunication links.

FIG. 3 shows a schematic representation of another example remotemonitoring system configuration, including a data collection unit thatcommunicates with sensors using individual wireless communication links.

FIG. 4 shows an example sensor used in the remote monitoring systemsshown for example in FIGS. 1 and 2, the sensor being placed in amonitoring station housing and connected to a cable which communicateswith the data collection unit.

FIG. 5a and 5b show two views of an example monitoring station housinglid and attached monitoring device, with sensor circuit thereon, for usein connection with a remote monitoring system of the present invention.

FIG. 6 shows a schematic representation of an example controller for usewith the remote monitoring system of the present invention.

FIG. 7 shows a graph illustrating an example 48-hour reading for SensorZones 1-5 for an example remote monitoring system of the presentinvention.

FIG. 8 is a chart setting forth the data plotted on the graph of FIG. 7.

DETAILED DISCLOSURE OF THE INVENTION

The preferred embodiment of the subject invention pertains to novelmethods and apparatuses to monitor for biotic and abiotic factors. Thedescribed methods and apparatuses can be used, for example, to monitorfor pests of the order Isoptera, and is particularly useful formonitoring populations of subterranean termites. It would be readilyapparent to persons of ordinary skill in the art that the method andapparatuses are adaptable to, for example, a variety of pest species.For purposes of brevity, however, the emphasis herein is directed tosubterranean termites.

The preferred embodiment of the invention is an integral part of anintegrated pest management system featuring two repeatable steps: (1)population monitoring/capturing (hereinafter referred to as monitoring),and (2) delivery of a toxicant to a pest through the use of atoxicant-containing matrix. The monitoring step of the process comprisesmonitoring particular location or locations to detect any termiteactivity. This step may further comprise capturing termites. Thetoxicant delivery step involves providing a slow-acting toxicant in amatrix which is eaten or otherwise contacted by the termites. Theslow-acting toxicant allows termites to return to and move through theircolony territory before dying. Nestmates then follow the trail back tothe toxicant. As described more fully herein, the two principal stepsdescribed herein can be repeated as part of a pest management programwherein the program involves the initial step of monitoring for pestactivity followed by control if pest activity is observed. Once controlis achieved, monitoring can be continued. The steps may also beperformed simultaneously. A suitable monitoring/control apparatus andmethod of use is disclosed in International Publication No. WO 93/239998(Dec. 9, 1993), the disclosure of which is incorporated herein byreference.

One example of how methods of the subject invention can be applied tothe control of subterranean termites is as follows:

A hole of appropriate dimension can be made in the soil for positioningof the station housing. The station housing is placed into the hole. Themonitoring device is placed inside the station housing. A cover can beplaced over the station housing and the cover secured to the surface ofthe ground. Alternatively, the monitoring device can be placed insidestation housing which is then inserted or hammered into the soil untilthe station housing opening is near the soil surface. Also, themonitoring article or station housing may be placed horizontally on theground or beneath the soil surface.

The monitoring device can be interrogated periodically for evidence oftermite infestation. Inspection of the monitoring device can beperformed weekly, bi-weekly, monthly, etc. as needed or desired. Becausetermites are known to chew through soft metal, thin strips of conductivemetal may be incorporated into the monitoring device and connected to anelectronic device. When termites chew through the thin metal, thecircuit is broken, thus evidencing the presence of termites.

A preferred remote monitoring system of the present invention is shownschematically for example in the figures. The system includes sensorsthat are strategically located about the target area. Given theparticular application of the present invention described herein, eachsensor preferably includes a monitoring device or block, such ascellulose or another material which is edible by termites, having anassociated bridging circuit through which termites are capable ofchewing. The monitoring device, including the associated bridgingcircuit, are placed within a monitoring station housing.

In one embodiment, each bridging circuit of each sensor is connected toa cable which links the sensor with an on-site data collection unit.Various runs of cables may be used to create a plurality of individualzones of sensors so as to provide more detailed information regardingthe precise location of detected termite activity, each zone having itsown individual cable link to the data collection unit. In this way thepresence of termites in one zone may be determined independently ofother zones.

Each zone may contain a few as one sensor, as is shown for example inFIG. 2, or as many as a plurality of sensors, as is shown for example inFIG. 1. Instead of hard-wire components, such as cables, the system mayinstead be configured such that the sensors communicate with the datacollection unit over independent wireless links formed using wirelesscommunication devices, as shown for example in FIG. 3. The on-site datacollection unit is configured to register data relating to each sensoror groups of sensors either continuously, or at regular intervals (suchas hourly, daily, weekly, etc.), or pursuant to a specified schedule, oron demand (real-time monitoring).

A remote host processor, such as a computer for example, is programmedto retrieve or down load data from the on-site data collection unit viaa communications link, such as a standard telephone land line orwireless communication means. Again, the down loading of suchinformation may occur either continuously, or at regular intervals(monthly, bi-monthly, quarterly, bi-annually, etc.), or pursuant to aspecified schedule, or on demand. The data may then be stored, recorded,reviewed and/or analyzed at a remote location. The down loaded data insystem described herein may be used for a variety of purposes by, forexample, pest control personnel, inspectors, property managers, and/orregulatory agencies.

When the communication link between the host computer and the datacollection unit is a telephone line that supports both voice and datacommunications, a voice/data recognition switch or sensor is preferablyused in association with the data collection unit so as to direct anycommunications requests placed by the host computer directly to the datacollection unit, rather than unnecessarily disturb those individualsattending to voice communication operations on the telephone line.Alternatively, a separate line may be use for such communication.

More specifically, the host computer shown for example in FIG. 1 islocated at a remote location and is preferably programmed toperiodically establish communications with the data collection unit.Once communications are established, the host computer presents anidentification protocol to the data collection unit so as to gain accessto the information communicated by the unit. Once access is established,the host computer issues a command to the data collection unit so as toinitiate the down loading of data maintained in a memory storage deviceportion of the data collection unit.

The data collection unit shown for example in FIG. 1 includes the memorystorage device on which are stored instructions to be carried-out by thedata collection unit to collect data relating to the sensors. The memorystorage device may include conventional memory chip or hard diskcomponents. Collected data is retained in the storage device foranticipated retrieval by or down loading to the host computer. In thecase of monitoring on demand or real-time monitoring, a data storagedevice is not needed. The data collection unit also includes multipleports or input/output (I/O) outlets which may be used to connect thecables that provide the communication between the sensors and the datacollection unit. The data collection schematically represented in FIG.1, for example, communicates with two independent zones of sensors; Zone1 having six sensors therein, and Zone 2 having five sensors therein.The data collection unit schematically represented in FIG. 2, on theother hand, communicates individually with a plurality of independentsensors. Further, a modem and related software are provided to establishthe necessary communications link when the data collection unit isaccessed by the host computer.

All of the above data collection unit elements may be incorporated intoa Programmable Logic Controller. Alternatively, a suitable datacollection unit may be configured using either a Personal Computer (PC)or a compact single board. The data collection unit may interface withthe sensors through an analog/digital converter. Regardless of itsprecise construction, the data collection unit can be programmed toregister data relating to line continuity, circuit resistance, moisture,and other conditions that can be sensed and identified using electronicsignals and sensors. The data registered by the on-site data collectionunit of the preferred system, for example, relates to at least oneelectrical circuit characteristic, such as for example line resistanceor line voltage.

The preferred remote monitoring sensor for the termite applicationdescribed herein is shown at FIG. 4, for example, disposed within amonitoring station housing. A thin line (ca. 2 mm width) of silverparticle (<10 microns) is drawn in a zigzag pattern on the surface ofthe monitoring device, using a circuit works conductive pen. Anotherlayer of plastic film may thereafter be placed over monitoring device soas to envelope the circuit for protection of the circuit from potentialcorrosion. The drawn circuit on the monitoring device interfaces withthe zone cable to establish a close circuit. The monitoring device,including its respective drawn circuit leads, is preferably removablyconnected to the underside portion of the monitoring station housing lidusing electrically isolated conductive clips, as shown for example inFIG. 5a. As shown in FIG. 5b, for example, each of the terminalsdisposed on the top surface of the monitoring station housing lid is inelectrical communication with the underlying clip to provide forconvenient connection of the sensor bridging circuit to the associatedcable.

The preferred remote monitoring device is composed of cellulosematerials that are intended to be fed upon by termites. As shown forexample in FIG. 4, the sensor, or monitoring device with associatedcircuit, is placed in the monitoring station housing that is planted insoil. Termite feeding in sensors can be readily detected as termiteseasily chew through the relatively thin circuit tracing while chewingthe cellulose material. Preliminary studies indicate that, even under ahumid and warm climate, the sensor circuit may remain conductive for along as six months or more in the absence of termite activity.

A sensor placed in humid soil, however, may absorb sufficient moistureto become conductive under certain conditions even when the circuit isbroken by termite feeding. This situation may be avoided through the useof analog signals to test the circuit, rather than digital signals. Byquantifying the drastic increase in circuit resistance (using the analogsignals) when the circuit is broken by termites, instead of usingqualitative testing of the circuit conductivity (using digital signals),the frequency of false positive as a result of moisture or otherexternal influences can be minimized or even eliminated altogether.

A prototype remote monitoring system was constructed using two8-conductor cables (in and out) connecting a total of eight sensors andthe I/O ports of a Compact-984 Controller (984-A120 Compact ProgrammableController, MODICON, Inc., Industrial Automation Systems, One High St.,North Andover, Mass. 018450). The architecture of the controller isshown schematically, for example, in FIG. 6. The controller wasprogrammed with a ladder logic software Modsoft Lite™ (371SPU921000,MODICON, Inc.) that used to constantly monitor the integrity of theelectric circuits of the eight connected sensors. Modsoft Lite recordsthe time and the date of the event, i.e. circuit interruption, andstores the data in the controller memory. An internal modem in thecontroller allows the stored information to be down loaded to a hostcomputer via telephone line. A voice/data recognition switch (Fax LineManager™, Technology Concepts, Inc.) was connected between thecontroller's modem and the telephone outlet to direct the call made bythe host computer to the Compact-984 Controller. The Modsoft Lite wasalso loaded in a host computer (4DX-66V, Gateway 2000, 610 Gateway Dr.,N. Sioux City, S.D. 57049) equipped with an internal modem (TelePathData/Fax modem). After establishment of communication between the hostcomputer and the Compact-984 Controller using Crosstalk™ (DigitalCommunications Associates, Inc.), data stored in the Compact-984Controller was down loaded using the Modsoft Lite.

In a preliminary experiment, four of the eight sensors were exposed to alaboratory colony of the Formosan subterranean termites, while the otherfour sensors were left in sand without termite activity. Within a weekof exposure, the time and date of circuit interruption or breakage ofthe four sensors exposed to termites were accurately recorded and downloaded to the host computer.

A second prototype remote monitoring system included a datalogger(CR10X, Campbell Scientific, Inc., Logan UT), or data collection unit,that communicates with five independent zones of sensors placed in soilsurrounding a house structure. A multiplexer (AM416, CampbellScientific, Inc.) is incorporated into the datalogger to allow thedatalogger to monitor multiple I/O ports relating to the various sensorzones. The datalogger is designed to check circuit integrity by applyinga voltage of 2,500 mV to each zone. When a given zone circuit iscontinuous, the voltage registered by the datalogger is approximately2,500 mV. The multiplexer is programmed to examine the circuit integrityat a set interval, and the data is stored in the Static Random AccessMemory (SRAM) of the datalogger. A Selective Ring Call Processor (SR3,Multi-Link, Inc., Nicholasville, Ky.) is placed between the incomingtelephone line of the house and the datalogger. A RingMaster service waspurchased to obtain a second telephone number with a distinctive ringfor the telephone line of this house. A host computer (Dell DimensionXPS P166c) is configured to dial the datalogger, which is locatedremotely with respect to the host computer, using the RingMastertelephone number. The SR3 device senses the distinctive ring assignedfor this number and directs the incoming host computer call to thedatalogger. The host computer then establishes the communications linkwith the datalogger and downloads stored data relating to circuitcontinuity. If desired, the host computer can be programmed to auto-dialthe datalogger at any time or ant any desired interval.

Data obtained using this second prototype system is set forth at FIGS. 7and 8, showing circuit interruption in Zones 1 and 3 during an example48-hour reading for five-zones. A line voltage of approximately 2500 mVwas applied to the sensor circuit. A registered line voltage ofapproximately 2500 mV was obtained when the circuit was tested, providedcircuit integrity was maintained. If the circuit was broken (as it wouldbe by sufficient termite activity), however, the registered line voltagedeviated significantly from the 2500 mV value.

Specifically, Zone 1 was intentionally broken as a part of thepreliminary experiment to simulate termite feeding. Accordingly, theregistered line voltage in Zone 1 fluctuated during the course of the48-hour test. Similarly, Zone 3 was intentionally broken between 1000hour and 2000 hour, resulting in a fluctuating registered line voltage.The marked differences in the character of the registered line voltagesfor Zones 2, 4 and 5 as compared to Zones 1 and 3 demonstrate how actualtermite feeding in a particular zone of a target area can evidenceitself through the use of the present invention.

Although the sensors described herein for the remote monitoring systemare designed to use circuit interruption to detect the presence oftermites, other sensors such as moisture meters strategically placed instructural wood to detect potential moisture problem, acoustic emissiondevices to detect feeding activity of other wood destroying insects suchas drywood termites, powderpost beetles, wood borers, or a miniaturedigital balance for measuring weight loss of cockroach or ant baitstations, may be used in accordance with the present invention.

Upon the detection of the presence of termites in the monitoring device,the monitoring device can be removed from the station housing (or soil)and replaced with a toxicant-containing matrix, in a toxicant deliverydevice (bait tube). Termites that are captured in the monitoring devicecan be extracted and gently tapped into an upper chamber of the toxicantdelivery device. This upper chamber is the recruiters' chamber. In orderto exit, the termites must then move through the toxicant-containingmatrix to reach the exit points. No toxicant needs to be used unlesstermites are detected from the monitoring procedure (or are otherwiseknown to be present), thereby eliminating the use of any unnecessarytoxicant. When termites are detected, the toxicant-containing matrix isutilized until no termite activity is detected in the toxicant deliverydevice. At that time, monitoring devices can be used again. In additionto the practice of replacing monitoring devices with toxicant deliverydevices, another embodiment of the invention comprises a monitoringdevice which remains in place and a toxicant delivery device which canbe added to, or fitted around, the monitoring device if the need arisesto deliver toxicant.

The various methods, materials and apparatuses for preparation oftoxicant-containing matrices, including matrices treated with dyesand/or hexaflumuron, will be readily apparent to those skilled in theart. Moreover, the various methods, materials and apparatuses forpreparation of various station housings, including horizontal stationhousings and station housings for above-ground monitoring and toxicantdelivery, will also be readily apparent to those skilled in the art.Moreover, those skilled in the art will recognize that the procedures,materials, and apparatuses of the present invention can be readilyadapted for use for the control of termites and/or other pests attackingcroplands, forests, golf courses, and other non-structural targets.

In sum, it should be understood that the examples and embodimentsdescribed herein are for illustrative purposes only and that variousmodifications or changes in light thereof will be suggested to personsskilled in the art are to be included within the spirit and purview ofthis application and the scope of the appended claims.

I claim as my invention:
 1. A system to monitor for termites in aplurality of zones, comprising:at least one termite sensor adapted forplacement in each of said zones, each of said termite sensors includingat least one monitoring block made of termite edible material and anelectrical conductor positioned adjacent to or embedded in the at leastone monitoring block, the electrical conductor being made of a materialthat is breakable by termite feeding, the electrical conductor forming acontinuous electrical bridging circuit such that when termite feedingbreaks the electrical conductor, the continuous electrical bridgingcircuit is broken; a data collection unit communicating with said atleast one termite sensor in each zone independently of termite sensorsin other zones, said data collection unit being capable of registeringthe presence of termites at any of said zones independently of otherzones; and a host processor for communicating with said data collectionunit from a remote location to retrieve data relating to the presence oftermites.
 2. The system to monitor for termites as set forth in claim 1,wherein said data collection unit communicates with said at least onetermite sensor in each zone through a cable extending independentlybetween said data collection unit and said zone.
 3. The system tomonitor for termites as set forth in claim 1, wherein said datacollection unit registers a circuit characteristic for each of saidzones to determine the electrical integrity of said continuous bridgingcircuit at each of said sensors.
 4. The system to monitor for termitesas set forth in claim 1, wherein said at least one monitoring block isadapted to be received in a monitoring station housing.
 5. The system tomonitor for termites as set forth in claim 4, wherein said monitoringstation housing comprises at least one termite opening thereby providingtermite access to said monitoring block and said electrical conductor.6. The system to monitor for termites as set forth in claim 4, whereinsaid at least one monitoring block is adapted to be attached to aremovable lid of said monitoring station housing.
 7. The system tomonitor for termites as set forth in claim 6, wherein a bottom portionof said lid of said monitoring station housing includes electricallyisolated conductive clips to receive said at least one monitoring block,said conductive clips being aligned with respective ends of saidelectrical conductor and in electrical communication with terminalsdisposed on a top portion of said lid.
 8. The system to monitor fortermites as set forth in claim 1, wherein said data collection unitcommunicates with said at least one termite sensor through anindependent wireless lid between said data collection unit and saidzone.
 9. The system to monitor for termites as set forth in claim 1,wherein said electrical conductor comprises an electrically conductiveline of less than 10 micron silver particles on the surface of themonitoring block.
 10. The system to monitor for termites as set forth inclaim 9, wherein the monitoring block is enveloped by plastic.
 11. Amethod to monitor for termites in a plurality of zones, said methodcomprising the steps of:placing at least one termite sensor in each ofsaid zones, each of said termite sensors including at least onemonitoring block made of termite edible material, and an electricalconductor positioned adjacent to or embedded in the at least onemonitoring block, the electrical conductor being made of a material thatis breakable by termite feeding, the electrical conductor forming acontinuous electrical bridging circuit such that when termite feedingbreaks the electrical conductor, the continuous electrical bridgingcircuit is broken; establishing communication with said at least onetermite sensor in each zone using a data collection unit configured toregister the presence of termites at any of said zones independently ofother zones; and communicating from a remote location through a hostprocessor with said data collection unit to retrieve data relating tothe presence of termites.
 12. The method to monitor for termites as setforth in claim 11, including the step of communicating through said datacollection unit with said at least one termite sensor in each zonethrough a cable extending independently between said data collectionunit and said zone.
 13. The method to monitor for termites as set forthin claim 11, including the step of registering said data collection unitby using a circuit characteristic for each of said zones to determinethe electrical integrity of said continuous bridging circuit at each ofsaid sensors.
 14. The method to monitor for termites as set forth inclaim 11, wherein said at least one monitoring block is adapted to bereceived in a monitoring station housing.
 15. The method to monitor fortermites as set forth in claim 14, wherein said monitoring stationhousing comprises at least one termite opening thereby providing termiteaccess to said monitoring block and said electrical conductor.
 16. Themethod to monitor for termites as set forth in claim 14, wherein said atleast one monitoring block is adapted to be attached to a removable lidof said monitoring station housing.
 17. The method to monitor fortermites as set forth in claim 16, wherein a bottom portion of said lidof said monitoring station housing includes electrically isolatedconductive clips to receive said at least one monitoring block, saidconductive clips being aligned with respective ends of said electricalconductor and in electrical communication with terminals disposed on atop portion of said lid.
 18. The method to monitor for termites setforth in claim 11, including the step of communicating through said datacollection unit with said at least one termite sensor in each zonethrough an independent wireless link between said data collection unitand said zone.
 19. The system to monitor for termites as set forth inclaim 11, wherein said electrical conductor comprises an electricallyconductive line of less than 10 micron silver particles on the surfaceof the monitoring block.
 20. The system to monitor for termites as setforth in claim 19, wherein the monitoring block is enveloped by plastic.